“Recent five-year highs in consumer confidence and early retailer promotions appear to be serving as wind in the sails for the beginning portion of the holiday season, with consumers opening up their wallets early and often,” he said.

The comScore forecast of a 17 percent gain would outpace last season’s 15 percent increase and would be well ahead of the retail industry’s expectation for a 4.1 percent increase in consumers’ overall spending this holiday season.

“The strength leading up to and during the holiday season-to-date, in addition to a maximum 32 shopping days between Thanksgiving and Christmas, provide the basis for what we view as a fairly optimistic outlook for the 2012 online holiday shopping season,” Fulgoni said.

Meanwhile, Americans are likely to spend between 3 percent and 4 percent more on their holiday shopping this year than last, in an apparent sign of increased consumer confidence, according to a survey published on Wednesday.

The poll, conducted jointly by the Consumer Federation of America (CFA) and the Credit Union National Association (CUNA), found 12 percent of consumers said they would spend more on holiday purchases this year than last year.

That compares with just 8 percent of respondents who said the same thing when polled this time last year.

A statement accompanying the annual survey said that this year’s planned increase in spending by some consumers “may well reflect perceived improvement in their financial situation.”

“Our survey results suggest that holiday spending this year will likely rise by between 3 percent and 4 percent compared to last year,” CUNA’s chief economist Bill Hampel said.

“This represents the fourth year of gradual improvement in holiday spending plans since a sharp decline in such plans in 2008,” he added.

The telephone survey of about a thousand subjects, conducted between Nov. 9 and Nov. 13, found that many Americans are willing to part with more of their money this holiday season despite sizable financial constraints, including high mortgage payments, student loans and credit card payments.

People with lower incomes were more likely than well-off Americans to say that their financial circumstances had worsened this year compared to last, and were correspondingly less likely to report plans to spend as freely.